Ideas for exposed LDs?

[falchionsmight]

I've been busy working lately, so I only get to work on my lasers in the wee-hours of the morning... I got one drive, and sure enough, I screwed up the laser, at least as far as I can tell. When I first got the diodes out, I kept getting mixed up on which one was the IR and which was the Red. They both put out red light (I wasn't looking directly into the diodes, so thankfully I can still see). My red one burned through tape when I hooked it up to some batteries... I used NiMH AAA on it, thinking I could just connect the batteries (going with the Pulsar and Kenom's Dorcy Mini ideas... at least I think the dorcy mini is just connected to the battery without a driver board...) So it worked for a little bit. It still makes red light, but it doesn't burn, or even make a visible dot 3 feet away... :'( I'm pretty sure it's no good anymore.

The picture is of my first DVD burner... I don't remember which diode was Red or IR...

So I got another one, it arrived today, and I already got the diodes out. This burner was 18x, the first one was 16x, so I thought that this burner would have an awesome diode in it. I'm kinda disappointed to find that the diodes aren't in cans... I've got leads solder to them, and they still live... I'm hoping someone might have a good way I could make this open diode useable in a burner. I'm open to nearly all suggestions. Right now I have some PVC tubing and a copper tube about 1" long, it might make a decent heat sink for the diode if I can center it inside it... I'll post pics of the copper tube tomorrow. Thanks for any help.

P.S. Is it possible to use the IR diodes out of the DVD burners to burn stuff? If so, what kind of voltage do they run on? Are there any driver board designs that a electronics noob could build? Thanks again

 

[falchionsmight]

Sorry about the large pic ^, I keep forgetting about my camera being 7 MP... Anyway, I got some time, so I took some pics of my LD and my tube, First the LD!

Sorry the pics are in IR... it's the camera that is easiest for me to take quick macros with...

 

[falchionsmight]

Here's my copper tube... CSI style... still in IR

 

[falchionsmight]

And the inside of it.

 

[SenKat]

I have heard of many folks being able to work with the exposed LD's with no issues - so there IS hope....I just cannot recall who they are ! (DOH !) Since I have never run across any open cans, I am leary about offerring advice, but as long as you are careful, you may be able to make it work out just fine !

 

[Daedal]

Hey falchionsmight;

Sorry to hear about your deceased diode... :'( I have some good news for you though. I personally was weary of using open can diodes for the longest time, and killed a few in the process of learning, but I can tell you for a fact that if you stick the diode in an AixiZ module it works just as well as a closed can diode. It has less heat sinking and it is very susceptible to dirt and debris from anything since it has no protective layer as does its covered cousin.

If you want to build the drive circuit from scratch, refer to my post at the top of the stickies in the experiments and modifications section of the forum. It has a complete guide with pictures of the actual circuit built and the schematic.

I personally ran my last DVD burner diode using a Dorcy mini, and Kenom has a couple videos on how to do it. They are very easy to follow and very well made.

I wish you good luck and keep us updated on the status of your new burning laser
DDL

 

[falchionsmight]

Thanks SenKat and Daedal! Daedal, I just found your driver today, and I've been trying to read it in bits (lately, I've been working a lot, we have a new manager, and she had the idea that it'd be wonderful to work everyone their max availbility... I've been working 39 hours a week at a job that's supposed to be part time... ). I stopped by my local Radio Shack, well, I have two local ones. I have one at the mall where I work, and they have no selection of electronics stuff.. :'( So tomorrow I'll have to go see if the other one has a 100 ohm pot, and your LM317 device... I hope that's the right part number, I'll be sure to get the right one tomorrow. Do you know of any place where I can buy thermal epoxy? Radio Shack doesn't sell it anymore, at least the ones by me don't, even though Artic Silver's site says Radio Shack carries their product (maybe they just carry the heat sink compound...). Thanks again for the driver circuit, it's exactly what I was hoping to find! I'll keep you all posted on this if I get any further, or if I kill it completely ;D.

Daedal, you'd probably know this, are the IR diodes in the DVD burners cabable of being burners too? I figure it should put out a quite a few miliwatts, especially if it's able to burn CD's quickly... but all that happens on the one I have from my first DVD burner is that the housing gets hot very quickly.... What kind of mA and V should the IR diodes be at?

 

[Gazoo]

I had no trouble harvesting an open can diode on my first try, although I found it a bit more difficult to remove it from the DVD burner's heat sink. The trick aside from being very slow and careful, is to not touch anything in the diode's opening, and get it mounted in a module as soon as it is harvested. Or at least put it in something that will keep dust out of it until you are ready to mount it in a module. Other than this, they can be treated just as you would treat a closed can diode.

 

[falchionsmight]

Thanks Gazoo, I'd love to see how you put the diodes in the modules... cuz I can't think of any effective ways of doing it.... Right now I've managed to get the driver board partly assembled. It's putting out more volts than I'd like, but I'm keeping the mA low. It's about 180 mA most times, I've tried to get it to 220, or 300, but my pot doesn't like me (I had no luck finding 100 ohm pots, nor did I find 1 ohm, or 4 ohm resistors at Rat Shack...). Here's a pic, hopefully my LM317 still works, I was trying to adjust my pot, switched it out, and forgot to turn off the circuit... needless to say the LM317 got very hot... I burned my thumb on it. I'll work on it more tomorrow night. Thanks for all the help guys.

 

[Gazoo]

Looking at your picture and zooming in on it, it doesn't look anything like the diode I have. VaThink took a picture of his. Mine is exactly the same and is the one I thought you had.

I am having trouble getting the search filters to work for me at digikey. The one Daedal linked to is only a single turn pot. The one in his picture is a multi-turn pot. The advantage of the multi-turn is it makes it easier to adjust the current more accurately.

Well anyway, you do have a good start. I am sorry I can't be of more help with the diode you have.

 

[Gazoo]

BTW, what is the brand and model number of the DVD-ROM you removed the diode from?

 

[Daedal]

Looking sharp there falchionsmight. I like how everyone has those "helping hands" but me! I can't find them around here... lol

Was the diode turned up when you too the picture? It looks very uniform. Can we get some more close-ups of this thing? It looks nothing like any of the open cans I've seen before! The ones I've harvested looked like the one Gazoo linked as well.

Also, about the resistors. If you bought the package that I told you about, you can use the 1-Ohm resistors and just put 4 of them in series. -> --====--====--====--====-- Or you can use 2 of the 10-Ohm resistors and put them in parallel. That would give you 5-Ohm resistance, which maxes the circuit at 250mA.

Your LM317 should be fine if the current is still somewhat regulated. In one of my projects once I used 2 of them and I had them running that hot for about 3 hours. Other than a computer case fan blowing on them was nothing to save their life. I was actually running them at damn near their max (36V and 900mA each). Needless to say... THEY WERE HOT! But still worked If you want to help it out a bit, you can try and put a piece of metal on the little heatsink there just so you don't burn yourself with it. I have found out that at 300mA the thing after 5 min runtime would get warm, but not burning hot, maybe a bit hotter than warm . Although, at about 200-250mA they almost never get warmer than room temperature.

I hope that helps you some. If you need anything just let me know;
DDL

 

[Gazoo]

BTW, VaThink and I have asked on CPF if anyone has any specs for these open can diodes. I can't for the life of me find anything that resembles it when searching around on google. So if anyone knows where to find the data sheet, please let us know. Thanks..

 

[falchionsmight]

Gazoo, here's what I bought off eBay, the whole thing was $21.50 shipped, so I figure it was a pretty sweet deal, especially for 2 diodes, optics, and some motors. The model is a Samsung DVD Writer Model TS-H652, it was 18x, or at least that's what it claimed. I'll try to get some macro shots of my diodes tonight. I happen to have 3 that look like this. I got one when I opened a CD player, and the two that came out of this DVD burner. They really look like the LD is just slapped onto some metal to keep it stable, and to provide heat sinking, and then there are 4 pins on the back of the thing. I assume the other two are for the Photo diode, but the DVD burner didn't have them connected to anything, so I can't be sure of anything on that.

Daedal, thanks for the driver design. I'll probably drop into Radio Shack on my way to work today, and get me a very large pack of resistors, just so I don't have to dig through my vending machine egg of salvaged ones. As for the LM317... I might have sent a full Amp through it... As for the burn, no lasting damage, just pain from the inital contact.... I must solder too much, since burns don't last very long on my fingers anymore ;D

 

[falchionsmight]

Daedal, I forgot to mention that in my photo my LD was lasing. I had it at about 180 mA in that one. It melted eletric tape when I held it in front of the diode. Is there any way to regulate the voltage going to the diode? My circuit keeps putting out about 4 V when I'm using 4 NiMh batteries as the power source... I could be wrong about that, but I know it's been higher than the prefered 3 volts.

 

[Gazoo]

Thanks falchionsmight, some macros would help identify the diode. As far as the LM317, or any of the regulators in this series, they can take a beating and keep on ticking. They are thermally protected so if it gets too hot it will shut down. Of course it isn't recommended to take them over their thermal specs intentionally, but the protection is there.